PCA evaluation of Quantum Cascade Lasers as radiation sources for portable IRAS systems detecting amphetamines

This article presents a comparative study of the performances of PCA systems detecting illicit amphetamines based on their infrared absorptions in the emission domains of two External Cavity (EC) Quantum Cascade Lasers (QCL), i.e. 1550-1330 and 1405-1150 cm^-1 respectively. PCA allows the recognition of hallucinogenic amphetamines with a remarkable efficiency in both these spectral windows. In the 1550 - 1330 cmp^-1 range, PCA distinguishes the amphetamines according to their pharmacological activity (hallucinogens and stimulants), the results being similar to those obtained with the same pattern recognition method applied to full GC-FTIR spectra. The relatively larger dispersion of the cluster of stimulant amphetamines may result in a slightly lower selectivity. On the other hand, it allows the identification of molecular units smaller than their molecular skeleton. Therefore, the evaluated lasers are suitable for being used as infrared radiation sources for portable instruments detecting amphetamines.